High speed relay



Jan. 10, 1961 J. H. M NEILL ETAL 2,967,918

HIGH SPEED RELAY Filed April 50, 1958 2 Sheets-Sheet 1 i INVENTORS 45 465/ 49 CHARLES F WEST F/G 7 JOHN H MAC/VE/LL MARK R 77104450 W W/ATTORNEY Jan. 10, 1961 J. H. MacNElLL ETAL 2,967,918

HIGH SPEED RELAY Filed April 30, 1958 2 Sheets-Sheet 2 INVENTORS CHARLESF WEST is; JOHN H MAC/VE/LL 3/ BY MARK P. 7/10/0150 ATTORNEY HIGH SPEEDRELAY John H. Mac'Neill, Charles F. West, and Mark R. Thomson,Melbourne, Fla., assignors to Sorohan, Inc, Melbourne, Fla., acorporation Filed Apr. 30, 1958, Ser. No. 731,996

14 Claims. (Cl. 200-87) The present invention relates to multiplecontact relays and more particularly to an inexpensive multiple contactrelay which is capable of extremely rapid operation and which isexceptionally long-lived.

It is an object of the present invention to provide a multiple contactrelay of light weight and small size which may be rapidly andeconomically assembled from a plu rality of pre-fabricated parts.

It is another object of the present invention to provide a multiplecontact relay having a novel electromagnetic structure which insuresunusually rapid operation of the relay.

It is yet another object of the present invention to pro vide a relayhaving a counter-balanced armature structure in which thecounter-balancing members are physically disposed within the volumedefined by the remainder of the relay structure.

It is still another object of the present invention to provide amultiple contact relay structure having resilient pro-stressed contactmembers having a backing of a soft, malleable metal so that the contactstructure may be adjusted and positioned without having to develop apermanent set in the resilient members thereby to eliminate the loss ofpre-stressing of the contacts after several adjustments of the relativeposition of the various contacts.

In accordance with the present invention the multiple contact relayincludes an electromagnetic structure incorporating a C-shaped coremember and a coil structure having a distinct winding disposed on eachof the legs of the C. The legs of the C are tapered to provide portionsof relatively large cross-section adjacent the connecting member of theC-shaped core, and portions of lesser cross-sectional area adjacent theexposed ends of the arms. An armature is disposed adjacent the exposedends of the arms of the C-shaped core and the relatively smallcross-sectional area of the core adjacent the armature provides forconcentration of the flux therein so as to minimize flux leakage in thesystem. The relatively large cross-sectional area of the legs adjacenttheir intersection with the connecting member insures a magnetic pathhaving a relatively low reluctance and therefore permits the developmentof a relatively high fiux concentration throughout the system.

As indicated, the winding of the electromagnetic structure is dividedinto two coils with each disposed about a difierent one of the legs ofthe C-shaped core so as to maximize the heat dissipating surface of thecoils and to minimize the distance between the outermost turns of thecoil and the core thereof. This latter structure minimizes leakage fluxand therefore increases the eficiency of the structure. Further, thecore is laminated to reduce eddy current losses. As a result of thespecific structure recited, it is possible to build a relay structurehaving five or ten single pole, double throw contacts which may be movedfrom one set of contact conditions to another set of contact conditionsWithin two and one-half milliseconds after energization of the relaycoil.

The armature of the electromagnetic structure is lee counter-balanced inorder to prevent actuation by external influence (such as shock,vibration) and to permit reliable operation in the presence of shock andvibration. The armature is formed from a single stamping which may beappropriately shaped to provide a cross member, a pair ofcounter-weights and a pair of hinge pin receiving members; each havingmembers on opposite sides of the cross member. The basic armaturestructure may be readily modified for utilization with relays employingvarying numbers of contact stacks.

A large 'brass block is disposed generally above and forward of theexposed ends of the legs of the core of the electromagnet and thecounter-weights and hinge pin receiving members are folded at rightangles to the cross member of armature and lie along the side of thebrass block. The utilization of the folded armature permits thecounter-balanced armature to lie substantially wholly Within the volumedefined by the remaining elements of the relay structure. The armatureis rotatably secured to the structure by means of a hinge pin whichpasses through the hinge pin receiving members of the armature andthrough the entire width of the brass block. The large size of the brassblock permits the hinge pin to have a large cross-sectional area and bymaintaining the hinge pin fixed relative to the armature while allowingit to rotate with respect to the brass block, the rotational surfacearea provided between the hinge pin and the brass block is quiteconsiderable and Wear on the hinge pin is minimized.

The contact structure of the present invention constitutes one or moresets of stationary contacts and one set of movable contacts for eachgroup of contacts. The stationary contact structures are essentiallyidentical and constitute a pre-stressed, resilient finger, fabricatedfrom a material such as beryllium-copper, having a backing member of asoft malleable metal such as soft iron. The purpose of the soft ironbacking is to permit the contacts to be adjusted by bending the softiron member without requiring the resilient material to take a set. Inconsequence, the contacts may be adjusted whenever necessary withouthaving to apply a permanent set to the resilient material which materialafter a few such adjustments would otherwise lose its resiliency andthereafter could not produce the desired pressure between contacts. Inan extreme case the loss of resiliency could prevent the contactfro-mbeing maintained in a position where it can be engaged by itsassociated movable contact. All of the stationary contacts of one group,that is, all of the stationary contacts which are engaged by the movablecontact at the same time, are imbedded, adjacent one end, in anon-conductive plastic body. This construction eliminates therequirement, during assembly, of placing spacers between contacts of thesame group, contacts of adjacent groups and between the contacts andbolts which are employed for securing the contacts to the assembly. Thecontacts are mounted on top of and secured to the brass block and extendoutwardly over the electromagnet. The movable contacts are actuated by abasic frame structure that is also readily modified for use with varyingnumbers of contact stacks and which extends forwardly of the armatureover the electromagnet. The frame structure is provided with aninsulating body, such as nylon, secured to the end of the frame anddisposed under the ends of the movable contact members. Energization ofthe relay produces rotation of the armature and movement of the nylonbushing or cylinder in a direction to cause the movable contacts tobecome disengaged from the first set of stationary contacts and toengage the other set of stationary contacts.

The provision of the large contact area between the hinge pin and thebrass block, and the utilization of permanently pre-stressed, stationarycontacts insures an extremely long life for the apparatus. Oneproduction model wascycled through 25,000,000 cycles of operationwithout exhibiting any noticeable wear.

The friction between the hinge pin and the brass block althoughinsufiicient to produce appreciable wear, does have an effect upon thetime required for actuation of the contacts and therefore in a furtherembodiment of the invention, the hinge pin constitutes a hollowcylindrical member having a wick disposed therein. The wick ismaintained lubricated and the lubricant from the wick leaks through aplurality of transverse apertures in the pin and onto the bearingsurface between the brass block and the hinge pin, so as to maintain thesurfaces lubricated and reduce the frictional drag on the apparatus.

It is therefore yet another object of the present invention to provide amultiple contact high speed relay of relatively simple design and yetcapable of rapid opera" tion and having an extremely long life.

It is yet another object of the present invention to provide a relaystructure having an electromagnetic assembly in which flux leakage andcoil heating is minimized and in which eddy current losses aremaintained at quite a low value.

The above and still further objects, features and advantages of thepresent invention will become apparent upon consideration of thefollowing detailed description of one specific embodiment thereof,especially when taken in conjunction with the accompanying drawings,wherein:

Figure l is a vertical side elevational view of the relay of the presentinvention;

Figure 2 is a front elevational view of the apparatus of the presentinvention with the electromagnet and contact assemblies removed;

Figure 3 of the accompanying drawings is a top view of the apparatus ofthe invention with the contact structure removed;

Figure 4 of the present invention is a perspective view of the armaturestructure of the apparatus;

Figure 5 is a front view of the stamping employed to form the armatureof the present invention;

Figure 6 is a longitudinal cross-sectional view of a hinge pin which maybe employed with the apparatus of the present invention;

Figure 7 is a top view of a stationary contact assembly of the presentinvention; and

Figure 8 is a longitudinal cross-sectional view of another hinge pinwhich may be employed with the apparatus of the present invention.

Referring specifically to Figures 1 through 5 of the accompanyingdrawings, there is provided a base member 1 of non-magnetic materialwhich terminates at its left end, as viewed in Figure l, in an invertedU-shaped member 2 having an upper base member 3 and leg members 4 and 6.Its right end is bent up both to afford protection to the contacts, asWell as to facilitate mounting. An electromagnet 7 is secured to theupper surface of the base plate l by means of a pair of bolts 8, onlyone of which is illustrated in Figure l. The bolts 3 pass upwardlythrough the base fl, through a spacer 5, for holding the magnet 7 abovethe base 1, through a base member 9 of C-shaped core 13 of theelectromagnet 7 of Figures l and 3 and thread into a tapped plate on topof the core. The core 10 of the magnet further comprises a pair oftapered arms 11 and 12 which extend from the base 9 toward the forwardleg 6 of the U-shaped portion 2 of the base member 1. The coil forenergizing the electro-magnet 7 constitutes two distinct windings 13 and14 which are disposed about the legs 11 and 12 of the core 10,respectively.

A block 17 of nonmagnetic, low friction, metallic material, such asbrass, is suitably secured to the'upper surface of the base member 3 ofthe U-shaped member 2, and is employed to support a contact structure 18of the electromagnet relay and further to provide a low-friction, longlife, pivotal support for an armature structure 19 of the relay.

The armature structure 19 and reference is now made particularly toFigures 4 and 5, constitutes a cross member 21 having a centrallyarranged, downwardly depending finger 22. The cross member 21interconnects two identical side members including upwardly andrearwardly extending counter-weights 23 and 24 and two forwardlyextending arcuate members 26 and 27 which are disposed above the crossmember 21. The members 23 and 26 are parallel to the members 24 and 27and are disposed perpendicular to the cross member 21. Actually, andreference is now made to Figure 5 alone, the armature is symmetricalabout a center line 28, and may be formed from a single stamping asillustrated in Figure 5. To form the completed armature, the originalstamping is bent at the locations designated by the reference numerals29 and 31 so that those portions to the left of the section 29 and thoseto the right of the segment 31 are disposed at right angles to thecenter portion 21 subsisting between the segments 29' and 31. Thearcuate segments 26 and 27 terminate at their forward ends forwardly ofthe cross member 21 and are provided with transverse apertures 32 and33, respectively, having a common center line coincident with the rearface of the cross member 21. The members 26 and 27 are notched as at 35to provide a generally horizontal surface for purposes which will becomeapparent.

The armature 19 is mounted on the relay by means of a hinge pin 34 whichextends through a suitable aperture in the brass block 17 and throughthe apertures 32 and 33 in the arcuate members 26 and 27, respectively,of the armature 19. The center of mass of the armature assembly lies onthe center line of the hinge p n, thereby providing protection againsteffects of shock and vibration. The entire U-shaped portion 2 of thebase of the mechanism is recessed along both of its external edges as at36 and 37 in Figure 2 so that the members 23 and 26 and 24 and 27 of thearmature 19 may be received within the width of the relay as determinedby the width of the base plate 1. In consequence, the armaturearrangement of the present invention provides a counterweighted orcounter-balanced element which is substantially completely confinedwithin the volume of the relay as determined by the dimensions of thebase plate It and the third dimension as determined by the upper surfaceof the contact structure 13. Further, the armature i9 is fabricated froma single stamping and therefore lends itself to rapid mass productiontechniques.

With the armature 19 mounted on the frame 1, by means of the hinge pin34, the cross member 21 is disposed just to the left, as viewed inFigure l of the accompanying drawings, of the ends of the arms 11 and R2of the electromagnetic structure '7. The downwardly depending finger 22of the armature structure 19 is disposed in an aperture 33 in the basemember 1 subsisting partially in the leg 6 of the U-shaped portion 2 andpartially in the base plate 1 centrally of the transverse dimen sion ofthese members. The aperture 38 is defined, in part, by a forward surface39 which in conjunction with the finger 22 limits counterclockwiserotation of the armature 19 about the hinge pin 34. Clockwise rotationof the armature 10 is limited by a screw 40 which is threaded into anaperture in the leg 6 and passes through an aperture in the leg 4 of themember 2. The screw 40 engages the rear surface of the cross member 21to act as a stop, and is locked in position in member 2 by a nut 45.

The hinge pin 34 is of such size relative to the apertures in the brassblock 17 and the apertures 32 and 33 in the armature 19 that it forms atight friction fit with the aperture defining surfaces of the armatureand rotates therewith while forming a snug fit with the brass block 17so that the pin rotates in the brass block and provides a largelow-friction, long-lived bearing surface for the pin. The hinge pin 34is tightly fitted to the armature 19 by means of a steel ball 50, seeFigure 6,

anemia which, after the armature is assembled on the block 17, is driveninto an aperture 55 in at least one end of the pin 34. The entire pin iscase hardened except in the region of the aperture 55 which ismaintained soft so that it can expand into tight contact with the wallsof the aperture 32 or 33. In consequence of the large contact area forthe hinge pin 34 and the counter-balancing of the armature 19, wear onthe hinge pin 34 is minimized and the life of the apparatus is greatlyextended over that obtainable with relays of more conventional design.

The specific mounting for the armature 19 not only greatly extends theuseful life of the apparatus, but also is instrumental in providing arelay which is capable of exceptionally rapid actuation, since thefrictional force that must be overcome is quite small. The other elementof the apparatus which is responsible for its rapid actuation is thespecific structure of the electromagnet 7. More particularly, thestructure of the electromagnet 7 is such as to minimize flux leakage andeddy current losses and further to minimize saturation of the corestructure within the range of operating flux for which it is designed.The low eddy current losses in the magnetic structure are due to theutilization of a laminated core. The minimization of flux leakageresults from the utilization of a core structure having tapered legs 11and 12 and further to the provision of a two legged member with one-halfof the required number of coil windings disposed about each of the legs.The tapering of the legs provides for concentration of the flux,developed by the electromagnetic structure, at the ends of the legs 11and 12 immediately adjacent the cross member 21 of the armature 19 andtherefore provides for maximum coupling of fiux between the corestructure and the armature structure. Further, the provision of twocoils, one disposed about each of the legs, provides for increasedcoupling between the coils and the legs over that which would beobtainable with a single winding. This structure increases efiiciencydue to minimization of leakage flux and also due to more efficientdissipation of heat developed in the coil windings 13 and 14.

Proceeding now to a description of the construction of the contactsection 18 of the relay, reference is made particularly to Figures 1 and7 of the accompanying drawings. In the embodiment of the inventionillustrated in the drawings, the relay is a single-pole, double-throwtype having a first group of five stationary contacts 41, a second setof five stationary contacts 42 and a set of five movable contact members43. The contact groups 41 and 42 are substantially identical and onlyone of the sets, for instance, the set 41, is described herein. Aspreviously indicated, the set of contacts 41 includes five distinctcontact members 44, each including a thin strip or finger 46 of apre-stressed hard metallic spring material, such as beryllium-copper,and a malleable metal backing member 47 of a material such as soft iron,in contact with one side thereof over a predetermined portion of itslength; such as, /a of the total length. The contact members are moldedin a suitable plastic 48 with the backing members 47 in intimate contactwith one side of the beryllium-copper strips 46 so that each contact setis an integral unit which may be rapidly assembled to the main relaystructure without having to individually assemble insulating washers,spacer strips, etc., as is the case with conventional relay structures.

The contact finger 46 extends forwardly of the backing strip 47 on thecontact side of the body 48 and is slitted at its end to provide twoindependent fingers 51 and 52. Each of the fingers 51 and 52 has a shortlength of precious metallic wire, or contact buttons 53 and 54,respectively, soldered, welded or brazed to the individual fingers so asto provide reliable contact surfaces for the relay. The end of the strip46 is slitted to provide two relatively independently movable contactmembers 53 and 54 so that a two point contact is insured rather than asingle point contact as would be the case if the member 46 were notslitted.

The hard metallic spring material which is employed for the fingers 46is so heat treated as to retain its resiliency indefinitely. The fingers46 are not easily bent to assume a permanent set. By comparison, inconventional relay structures, the stationary contact members are bentin order to align them properly with the movable contact member andinsure engagement between the two contacts. It has been found, however,that such members which are easily bent lose their permanent set or forvarious other reasons do not maintain a proper position with respect tothe movable contact and therefore it is necessary occasionally to resetthese fingers. After several adjustments, the pre-stressing is soon lostand then it is quite difficult to maintain a good contact or tore-establish a good contact between the movable contact and thestationary contacts. In accordance with the present invention, thestationary contact members are provided with the malleable backingfingers 47 which are used to position the contacts. The malleablematerial can be set and re-set indefinitely without destroying itsstrength and upon being set merely bends the finger 46 to the properposition without changing the pre-stress therein. Therefore, theberyllium-copper fingers 46 are not required to take a permanent setduring adjustment since all adjustments of these fingers may be made bybending the soft iron or backing member 47.

The invention has been described as utilizing berylliumcopper stripswith soft iron backing members. Obviously, other resilient pre-stressedmaterials may be employed for the contact members while other malleableand relatively strong materials may be employed for the backing members.In the contact groups 42 and 43, the fingers 46 extend rearwardly of thesupporting strips 47 so as to provide a surface to which lead wires maybe connected as illustrated in Figure 1 of the drawings.

The movable contact structure 43 includes five beryllium-copper contactfingers 56, and reference is now made to Figure 1 in which only one ofthe contact structures is illustrated, and a backing finger 57 also ofberylliumcopper. The members 56 and 57 also have a region adjacent oneend of each imbedded in a unitary plastic body 58 and the fingers 56 arelonger than the contact fingers 46 of the groups 42 and 41 so that theymay be contacted by the mechanism which is employed to operate theswitch contacts, as will be described subsequently. The plastic bodies4% and 58 are provided with a plurality of apertures such as theapertures 59 in the body 48, as illustrated in Figure 7, in order toreceive bolts 61 which are adapted to engage threaded apertures in thebrass block 17. In assembling the contact structure, one of the contactgroups, such as the group 41, is placed on top of the block 17 with itsapertures 59 aligned with the apertures in the block and then thecontact groups 43 and 42 are placed on top of the group 41 in the orderrecited. A plate 62 is placed on top of the plastic body of the group4?. and then the threaded bolts 61 are passed through the appropriateapertures and threaded into the brass block 17. It will be appreciatedthat the ease with which this structure may be assembled results fromthe utilization of plastic bodies in which the contact members areimbedded since with such construction, no spacing members or insulationmembers are required for insulating the contact bars from one another,from the body to which they are secured or from the bolts 61 with whichthey are secured.

The switching action is produced by movement of the fingers 56 of thecentral contact structure which carries two contact members 63 and 64 oneach contact bar. The contact members 63 are each either a short lengthof, or a button of precious metal secured to the under surface of thefinger 56 while the contact members 64 are each a short length or buttonof precious metal secured to the upper surface of the member 56. Thecontact members 63 and 64 are arranged to contact the members 53 and 54secured to the fingers 46 of the structures 43 and 42 and since theselatter are also of precious metal, the contact life is quite long.

In order to actuate the movable contact fingers 56, there is provided agenerally U-shaped frame 66 having a pair of arms 67 and 66 and a basemember 69. The arms 67 and 68 are secured respectively to the recessedportions 35 of the arcuate members 26, 27 of the armature 19. The basemember 69 terminates in its forward end in an upwardly turned flange orplate 71 having a hollow rectangular aperture 72, as viewed in Figure 2of the accompanying drawings. The rectangular aperture 72 defines alower bar 73 and upper bar 74). Disposed over the upper edge of thelower bar is a generally cylindrical bushing 76 which is slotted so thatit may be disposed over the upper edge of the bar '73. The cylinder 76may be fabricated from nylon or other suitable insulating material. Thespacing between the upper edge of the cylinder 76 and the contactstructures is such that the arms 56 of the movable contact group 53 justclear the cylinder and engage contact members 53 and 54 disposed on thecontact fingers 46 of the stationary group 41.

In operation, the energization of the electromagnet attracts the crossmember 21 of the armature l9 and effects counterclockwise rotation ofthe armature 19 about the pivot pin 34. Counterclockwise rotation of thearmature 19 about the pin 34 produces upward movement of the member 66and therefore upward movement of the cylinder 76 and of the contact arms56 so that the contacts 63 become disengaged from the contacts 53 and 54of the contact group 41 and the contacts 64 engage the contacts 53 and54 of the contact group 42. Therefore, energization of the electromagnet7 opens the circuit between the contact groups 41 and 43 and closes thecircuit between the contact groups 42 and 43.

The specific structure utilized lends itself to modification by theaddition of various sets of contacts. Specifically, some of the contactsmay be removed or the entire structure may be reduced in size to provideless than five sets of contacts or additional sets of contact groups maybe stacked on top of the contact groups 42, 43 and 44 and the movablecontacts of such a set may be actuated by a nylon cylinder fitted overthe bar 74 of the member 66. Therefore, the five, single-pole,double-throw relay may be readily converted into a ten single-pole,double-throw relay, or a five single-pole, single-throw relay, etc. Theillustrated frame 66 and armature 19 are basic structures which may beemployed with either one or two stacks of contacts. The structures areemployed in the form illustrated for two stacks of contacts but aremodified when employed with a single stack. For use with single stackconfiguration illustrated in the accompanying drawings, thecounterweights are cut back along the dashed lines 80, Figure 4, Whilethe frame 66 is cut along the dashed lines 65, Figure 2, to remove theupper bar 74. The contact stacks may be extended and actuation may beeffected by additional cross bars extending upwardly from the presentflange 71. Such an upward extension of the flange 71 and addition of anadditional nylon cylinder would require an increase in weight of thecounter-balance 23 and 24 which is readily effected by merely increasingtheir rearwardly extending length.

It is apparent from the above that the present invention provides arelay structure capable of rapid actuation and maximum life.Specifically, the rapid actuation is a function of the low frictionallosses in the bearing members and the specific structure of theelectromagnet 7. Further the counter-balancing of the armature preventsspurious operation of the contacts in response to vibration and shockand allows dependable operation in the presence of vibrationand shock.

A reduction of the frictional drag of the hinge pin 34 on the apparatusmay be effected by fabricating the hinge pin 34 as a hollow pin havingalubricant saturated wick disposed therein. The pin has a-plurality oftransverse poresor apertures for permitting the lubrication to escapefrom the hollow Wick to the friction surfaces. Such a pin is illustratedin Figure 8 and constitutes a hollow cylindrical metallic body; 81having a wick material 82 disposed therein. The wick material may bekept saturated with the suitable lubricant which is permitted to bleedonto the surfaces to be lubricated through a plurality of transverseapertures 83 which extend through the wall of the hollow cylinder 81. Bythis arrangement the friction at the hinge may be reduced as a result ofthe constant lubrication of the bearing surfaces. The hinge pin ofFigure 8 is also-adapted to be secured to the armature 19 by a steelball 84- that is received inone end of the pin.

The relay of the inventionis extremely compact and an important featurethereof is the fact that the counterbalancingweights 23 and 24 of thearmature 19 are almost wholly maintained within the volumetric limits ofthe apparatus as defined by the base structures 1 and 2 and the verticalheight as defined by the contact arrangement. As an indication of theoverall size of the relay, it is wished to point out that the structureillustrated in Figure l is almost twice the size of the actual relay.

While we have described and illustrated one specific embodiment of ourinvention, it will be clear that variations of the details ofconstruction which are specifically illustrated and described may beresorted to without departing fro-m the true spirit and scope of theinvention as defined in the appended claims.

What we claim is:

1. An electromagnetic relay comprising an electromagnet including atleast one pole having a pole face, a large body of low-friction,non-magnetic bearing material disposed adjacent said pole face, anarmature having a cross member disposed adjacent to and spaced from saidpole face, said armature further comprising a pair of members disposedgenerally perpendicular to said cross member and each lying on adifferent side of said body, each of said members including acounterweight and a curved member, and a hinge pin disposed in alignedapertures in said curved members and said body, said hinge pin beingsecured to said curved members and rotatable in said body, and thecenter of mss of said armature lying approximately on a center line ofsaid aligned aperture.

2. The combinationaccording to claim 1, further com prising at least onestationary contact member and one movable contact member, a frame membersecured to said armature and movable therewith, said frame member beingdisposed in contact with oneside of said movable contact member.

3. The combination according to claim 2, wherein said stationary contactmember comprises a flat prestressed, resilient finger and a relativelysoft, malleable finger in contact with said resilient finger over alarge area of one side thereof.

4. The combination according to claim 3, further comprising apluralityof stationary contact members and a plurality of movablecontact members, said stationary contact members having a regionadjacent one end of each imbedded in a single insulating plastic body.

5. The combination according to claim l, wherein said electro-magnetcomprises a C-shaped laminated core having tapered generally parallelpole pieces defining the legs of said C- shaped core, said pole pieceshaving a smaller cross-sectional area adjacent their pole faces thanadjacent their ends remote from said pole faces, and a distinctcoildisposed about each of said pole pieces.

6. The combination according to claim 1, wherein said body is disposedabove the plane of said electro-magnc-t and said cross member, andfurther including a plurality of contact members disposed above andsecured to said body, said contacts extending outwardly over saidelectin-magnet.

7. The combination according to claim 6, further comprising a framemember secured to said curved members and extending outward over saidelectro-magnet, said frame member having a cross piece disposed underand in contact with predetermined ones of said contact members.

8. The combination according to claim 1, wherein said body is disposedabove and generally forward of said electromagnet and above said crossmember, a plurality of stationary contacts having a region adjacent oneend of each imbedded in a non-conductive moldable body, a plurality ofmovable contacts having a region adjacent one end of each imbedded in anon-conductive moldable body, said moldable bodies being stacked oneabove the other on top of said body of low-friction, non-magneticbearing material and secured thereto, said contacts extending outwardlyover said electromagnet with each contact of one plurality of contactsaligned above a distinct contact of another plurality of contacts, aU-shaped frame member having legs and a base member, said legs havingtheir free ends secured to said curved members of said armature andextending outwardly over said electromagnet, said base member of saidU-shaped frame member being adapted to actuate all of said movablecontacts.

9. The combination according to claim 7, wherein each of said stationarycontacts comprises a finger of prestressed resilient material and afinger of soft malleable material, said fingers being in intimatecontact over a predetermined portion of their lengths and both havingone end imbedded in said moldable material.

10. The combination according to claim 9, wherein said pie-stressedresilient material is beryllium-copper.

11. The combination according to claim 9, wherein said malleablematerial is soft iron.

12. A stationary contact arrangement comprising a plurality ofelongated, pre-stressed, resilient members, a plurality of elongatedsoft malleable members, said elongated members each having a regionadjacent corresponding ends imbedded in an insulating, moldable materialwith each of said malleable members in intimate contact with one side ofa different one of said resilient members substantially along the entirelength of the shorter of the members.

13. The combination according to claim 12, wherein said resilientmembers are fabricated from berylliumcopper and said malleable membersare fabricated from soft iron.

14. The combination according to claim 1 wherein said hinge pin furthercomprises a hollow cylinder having one or more holes in the cylinderwall, and a porous material contained within said hollow cylindercapable of becoming saturated with a lubricant.

References Cited in the file of this patent UNITED STATES PATENTS789,814 McGrath May 16, 1905 977,114 Manson Nov. 29, 1910 1,503,090Carichoff July 29, 1924 1,639,901 Sampson Aug. 23, 1927 1,785,702Osborne Dec. 16, 1930 2,069,171 Merkel Jan. 26, 1937 2,134,448 Knos Oct.25, 1938 2,290,725 Bartels et a1 July 21, 1942 2,428,218 Herbst Sept.30, 1947

